Date 加减并重置为数字和日期

我对python非常陌生，我想知道如何从一个显示数字中加上或减去1，以及除了使用变量将数字加在一起或什么都没有找到的日期，但我似乎无法找到如何通过点击按钮来操作显示。。这有意义吗？这是我想到的任何帮助都将不胜感激

turtle.pencolor("black")
today = datetime.date.today()
difference1 = datetime.timedelta(days=-1)
company = today
site = today
writeTexts (site ,500,-215)
writeTexts (company ,-150,-215)
writeTexts (today ,500,-310)
turtle.pencolor("orange")
startValue= 0000
companyDay = startValue
siteDay = startValue
writeTexts (companyDay, -350,50)
writeTexts (siteDay, 300, 50)

GPIO.setmode(GPIO.BCM)
GPIO.Setup (17, GPIO.IN, pull_up_down = GPIO.PUD_DOWN)
GPIO.Setup (18, GPIO.IN, pull_up_down = GPIO.PUD_DOWN)
GPIO.Setup (21, GPIO.IN, Pull_up_down = GPIO.PUD_DOWN)
GPIO.Setup (22, GPIO.IN, pull_up_down = GPIO.PUD_DOWN)
GPIO.setup (23, GPIO.IN, pull_up_down = GPIO.PUD_DOWN)
GPIO.Setup (24, GPIO.IN, pull_up_down = GPIO.PUD_DOWN)
while True:
    try:
        if(GPIO.input(17)== 1): #alstom increment
            companyDay +1
            company +difference1
        if(GPIO.input(18)== 1): #alstom decrement
            companyDay -1
            company -difference1
        if(GPIO.input(21)== 1): #alstom reset
            writeTexts(companyDate ,-350,50)
            writeTexts(company ,-150,-215
        if(GPIO.Input(22)==1):  #site increment
            siteDay +1
            site +difference1
        if(GPIO.input(23)== 1):  #site decrement
            siteDay -1
            site -difference1
        if(GPIO.input(24)==1):  #site reset
            writeTexts(siteDay ,300,50)
            writeTexts(site ,500,-215)
            sleep(.01)
    except KeyboardInterrupt:
        exit()
GPIO.Cleanup ()

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所以我认为我有输入的概念，但我不知道如何实现它。如果你想修改变量，你需要使用+=和-=而不是+和-。